The invention refers to an accelerometer where a piezoelectric bender element is compressed and secured between two half blocks of a ceramic material (e.g. Al.sub.2 O.sub.3), having two distance gaps filled by a pourable sealing material. The bender element is sealed in by two cover plates and the contact recess is filled by watertight sealing material. Thus only the signal wires protrude from the surfaces, put on by metal sputtering or other known metallizing methods.
The outside dimensions of the piezobloc are chosen for optimum electrical output, at a selected frequency range which is especially suited for modal analysis of elastic structures, where a very strong signal, at a very modest element weight, is required. For such applications, the piezoceramic element yields a signal of at least a factor 5 higher than any other shear or compression type element of similar size or weight. Due to its higher thermal sensitivity, the bender element must be thermally protected, and this may be achieved by embedding it in a low conductivity material and by protecting it with cover plates on the sides. With these precautions, satisfactory thermal stability is achieved.
The advantage of the ceramic half blocks is evident also if the sensor element is to be equipped with integrated electronics. The half blocks may be strips of a ceramic material which are processed in multiple lots and after testing are cut into single elements. This batch processing, standard in microtechnology, allows volume production at low prices.